1. Field of the Invention
The present disclosure relates to a vacuum cleaner. More particularly, the present disclosure relates to a multi cyclone dust-separating apparatus of a vacuum cleaner, which draws in an external air and then separates dust or dirt by several stages therefrom.
2. Description of the Related Art
In general, a cyclone dust-separating apparatus provided in a vacuum cleaner is an apparatus, which whirls air laden with dirt or dust and separates the dirt or dust therefrom. Such a cyclone dust-separating apparatus has been recently widely used because it can be semi-permanently used without any inconvenience of frequently replacing dust bags.
The cyclone dust-separating apparatus usually has a single cyclone structure, which includes a cyclone to make drawn-in air into a whirling current and thus to separate dust or dirt from the drawn-in air, an air inflow part to guide the drawn-in air to flow into the cyclone in a tangential direction thereof, and a dust collecting bin to collect and store the separated dust or dirt therein. The cyclone dust-separating apparatus having the single cyclone structure as described above separates all of large dust or dirt, medium dust or dirt, and minute dust or dirt from the drawn-in air at once. Accordingly, relatively large and heavy dust or dirt can be easily filtered, but relatively minute dust or dirt, such as particle, is apt to be discharged as mixed with the air. As a result, the conventional cyclone dust-separating apparatus presents a problem that a dust-separating efficiency is deteriorated.
To address the problem as described above, in recent, a multi cyclone dust-separating apparatus in which a plurality of cyclones is installed to separate dust or dirt by several stages from drawn-in air is actively developing. Such a multi cyclone dust-separating apparatus is advantageous in that since it separates the dust or dirt in the several or multiple stages, it can remove even minute dust or dirt, such as particle, thereby increasing a dust-separating efficiency. However, in the multi cyclone dust-separating apparatus, there is a problem that since a cyclone body of each of the cyclones is formed in a linear cylinder shape, the diameter of which is uniform in a longitudinal direction thereof, or a shape having a truncated cone portion at a lower part thereof, the drawn-in air increases its flowing speed when it is discharged through an air discharging part of the cyclone body after flowing into the cyclone body. Such an increase in the flowing speed of the air at the air discharging part not only increases a pressure loss, but also increases an operating noise. The increase in the pressure loss may increase an output of a suction motor of the vacuum cleaner, which is required to obtain the same dust-separating efficiency, thereby causing the vacuum cleaner to use more power.